Patent GB-1253233-A (GB)
IPC: B23B39/20
Filed: 1968-10-22
Abstract: 1,253,233. Indexing; tool turrets. MULHEAD Ltd. 21 Oct., 1969 [22 Oct., 1968], No. 50056/68. Headings B3B and B3C. A tool turret 12 (Figs. 1 and 3) in a machine tool is of generally frusto-conical or frustopyramidal form and is mounted to rotate about an inclined axis AA such that its operative tool bearing face lies in the vertical plane. The turret includes drive and clutch means for transmitting drive from a common motor 18 to any of the tool heads 22 when located in the operative station 1. The turret is mounted on a base 11 arranged for fast and slow feed by means of slide members 13 on slides 14. Turret indexing.-Indexing of the turret is effected by a cam 39 (Figs. 3 and 6) mounted on a transverse shaft 95 in the base 11 and driven by a motor 20, the turret carrying a series of circularly spaced follower rollers 34. A locating shot bolt 101 (Figs. 3 and 9) having a tapered nose portion is arranged to enter one of a series of circularly spaced tapered recesses 100 in the turret to locate the turret accurately in its indexed positions, the shot bolt 101 being operated by means of a face cam 97 mounted coaxially with the index cam 39. Motion is transmitted to the shot bolt 101 by means of a follower roller 112 and pivotal lever 110 with forked end 103, a resilient spring connection being provided between the lever 110 and the bolt to accommodate slight differences in the degree of entry of the bolt into the various recesses 100. Tool drive.-A further cam 96 (Fig. 6) is mounted coaxially with and is driven together with the indexing and bolt-operating cams 39, 97 and controls the connection and disconnection of a dog-clutch 84, 85 (Fig. 3) to complete and disconnect the drive to the tool heads at the station 1 in suitably timed relation to the indexing movements. Turret clamping and lifting.-The turret rotates about a central upstanding spigot 28 attached to the base 11 and forming with a cylindrical portion 41 of the turret a piston and cylinder assembly admission of hydraulic pressure to which serves either to clamp the turret firmly on the base 11 or to lift the turret slightly therefrom to facilitate indexing. Compressed air or other pressure fluid is supplied through constrictors 33 during the indexing operation to a series of shallow pockets 32 spaced around the periphery of the turret base 11 to reduce friction and thus also facilitate indexing. Tool feed.-A polygonal turret feed control bar 123 (Fig. 12) is indexably mounted at the side of the slide 13 and carries a series of trip cams 120 ,121 on its various faces the cams being adapted to control the fast traverse and slow feed of the turret through switches 170, 171. A back stop switch 164 is controlled by a trip cam 162 mounted on the slide itself. Turret bar indexing.-Indexing of the turret feed control bar 123 is derived from the linear movements of the shot bolt 101, an extension 101a of which is connected to a forked member 146 drivingly mounted on an input shaft 143 of a 2 : 1 step up gear-box. The latter drives a pawl carrier 140 having a square section spring loaded pawl 144 a chamfered end of which cooperates with a ratchet wheel 132 having wedge shaped ratchet lugs 133 (Fig. 15). Indexing movement is transmitted from the ratchet wheel 132 through a one-way clutch assembly 131 to the bar 123. A spring loaded detent 156 cooperates both with the pawl carrier and with the ratchet wheel 132 to hold the bar against reverse movement.